Boiler relief device



Aug. 6, 1940.

J. PODOLSKY BOILER RELIEF DEVICE Filed Dec. 12. 1954 5 Sheets-Sheet l l/wvezfof" Jar/606 Podo SPL? Aug. 6, 1940. J. PQDOLSKY 2,210,555

' BoILER RELIEF DEVICE,

Filed Deo. 12, i934 y5 sheets-sheet 2 .wvewfow Aug. e, 1940.

J. PoDoLsKY BOILER RELIEF DEVICE 5 Sheets-Sheet 5 Filed Dec. 12, 1934 oooooooo ooooo Aug- 6 1940 J. PoDoLsKY 2.210,5'55

BOILER RELIEF DEVICE Filed Dec. l2, 1934 5 Sheets-Sheet 4 w H m .w .MU N f y 0 4. M

4Z ze Patented Aug. s. 1940 UNITED STATES PATENT "oFFlcE 16 Claims.

The present invention relates to boiler accessories. and more particularly to relief devices and the like for boilers designed to supply hot water for domestic purposes.

Domestic boilers of the above-described character are commonly provided with a pressure valve that is normally closed, but that opens automatically upon the pressure in the boiler becoming higher than a predetermined, safe value; a normally closed, temperature-controlled passage that similarly becomes opened automatically when the temperature becomes dangerously high; and a normally closed, vacuum valve that opens automatically when, the supply of water from the mains failing, the pressure in the boiler becomes so excessively low that there might be `danger of the boiler collapsing by atmospheric pressure. These have, in many cases, been provided with a common valve inlet and a common valve outlet.

In constructions of the above-described character at present in use, the temperature control is very inefllcient. The normally closed, temperature-controlled passages do, it is true, become automatically opened upon the occurrence of excessive temperatures, thus permitting the overheated water and steam to escape therethrough. Such escape is, however, followed by an inrush into the boiler of cold water from the mains, and this inrushing cold water takes place along a path such as to tend to prevent further outflow of the hot Water and steam.

An object of the present invention, therefore, is to improve upon present-day constructions of the above-described character, to the end that the iniiowing cold water and the outflowing hot water and steam shall be along diierent paths that shall not interfere with each other.

Owing to the nature of the constructions heretofore in use, both of the boiler and the relief devices, as Well as the connecting mechanisms, it has, up to now, been considered practicable to install these relief devices only at points removed at a substantial distance from the boiler, to one side of the direct path of flow of the water from the mains to the boiler. Usually, the relief devices have been located in or near some pipe connected at an angle to the water pipe. 'I'he pressures, temperatures and vacua before described must, indeed, therefore, under such conditions, reach excessive values before they can produce any appreciable effect upon the said relief devices.

In case of rising temperature, for example, and

v if the temperature-controlled device is positioned at some distance away to oneside of the water pipe, the temperature must rise high enough to heat the cold water in a long water-supply pipe and also the Water in the pipe that branches off therefrom before it can have any effect upon the temperature-responsive device. It is perfectly 5 possible, therefore, under certain, fast-changing conditions, for the damage attempted to be guarded against to occur, wholly or in part, before the relief device can respond.

It is accordingly a further object of the pres- 10 ent invention to improve upon'constructions of the above-described character, to the end that the relief devices shall be promptly responsive to abnormal conditions of temperature, pressure and/or vacuum.

With this end in view, a feature of the invention resides in a novel structure that is adapted to be situated at a suitable spot in, or very near to, the boiler itself, where the said abnormal conditions have their origin. 20

A further object is to provide a novel structure for one or a plurality of relief-controlling elements.

Other and further objects will be described hereinafter and will be particularly pointed out 25 in the appended claims.

The invention will now be more fully described in connection with the accompanying drawings,- in which Fig. 1 is a perspective of a boiler relief device constructed according to a preferred embodiment of the present invention, shown attached to the upper part of a domestic boiler; Fig. 2 is a perspective, upon a larger scale than Fig. l, with part of the casing of the relief device in vertical section; Fig. 3 is a vertical section taken upon the line 3-3 of Fig. 5, looking in the direction of the arrows; Fig. 4 is a vertical section taken upon the line 6 4 of Fig. 3, looking in the direction of the arrows; Fig. 5 isa horif zontal section taken upon the line 5-5 of Fig. 40 4, looking in the direction of the arrows; Fig. 6 is a vertical section taken upon the line 6-6 of Fig. 4, looking in the direction of the arrows; Fig. 'l is an elevation similar to Fig. 1 of a modification; Fig. 8 is a perspective similar to Fig. 45 2 of the modification shown inFig. 7, the section being taken upon the line 8-8 of Fig. 9, looking in the direction of the arrows; Fig. 9` is a vertical section similar to Fig. 4 of the modification shown in Fig. 7, the section being taken upon the line 50 9-9 of Fig. 8, looking in the direction of the arrows; Fig. 10 is a vertical section similar to Fig.

3 of the modification shown in Fig. 7; Fig. 11 is a perspective similar to Figs. 2 and 8 of another modification; Flg. 12 is a vertical section 55 similar to Figs. 4 and 9 of still another modliflcation; and Fig. 13 is a perspective similar to Figs. 2, 8 and 11 of still a further modification.

A domestic, hot-water boiler 2 is illustrated in Figs. 1 and 7, provided at its top with a coldwater, inlet, supply pipe 4 and with a hot-water, outlet pipe 5. The illustrated boiler 2 is of the type commonly employed in homes for storing hot water for kitchen yor bathroom purposes, and is frequently referred to as a hot-water, storage tank, but the invention is obviously not limited to this particular type of boiler. The cold water enters the boiler through the` inlet pipe 4, and into a casing 8, from which it travels downward, by way of a short connecting pipe I8, as shown in Fig. 1, or II, as shown in Fig. '1, into a pipe 1 in the boiler 2,`to a point a very short distance, say, six inches, above the bottom of the boiler 2. 'I'he inlet pipe 4 screws into a cold-water inlet opening 9, leading into the casing 8. 'Ihe casing 8 is shown in Figs. 1 to 6, vertically inverted with respect to the showing in Figs. 7 to 13, and it may occupy also other positions, such as the horizontal.v

' In a wall I2 of the casing 8, directly in the path of the incoming cold water, as illustrated more particularly in Figs. 3, 4, 5, 9 and 10, there are disposed two or three of the following relief elements, a pressure valve I4, a temperature device I6 and a vacuum valve I8. For brevity, and to save clrcumlocution of language, these combined elements may together be referred to as a relief device. The relief device may, of course, be constituted of one or two only of the relief elements, and it may, on the otherhand', embody more than three relief elements. A pressure valve and a temperature-controlled element only, omitting the vacuum valve, are illustrated in Fig. 11, a temperature-controlled element and a vacuum valve only, omitting the pressure valve, in Fig. 12, and pressure and vacuum valves only, omitting the temperature-controlled element, in Fig. 13.

The pressure valve I4 is shown as comprising a valve body 28, held downward upon a valve seat 22 by a coil spring 24, confined in a housing 26. When the pressure in the boiler 2 rises above a predetermined, safe value, the excessive pressure will be communicated, through the pipe I8 or II, to the chamber in the casing 8, and against the wall I2, causing the valve body 28 to move from its seat 22, in opposition to the force exerted by the spring 24. 'I'he hot water in the boiler, under pressure, will then escape into the housing 28, and through an opening 28 therein, into a chamber formed between the wall I2 and a threadedly removable cover member 38; and from the said chamber, by way of an opening 32 in the 'cover member 30, into a relief, outlet or drain pipe 38. Cold waterwill soon enter the boiler by way of the pipe 4 and the pipe I8 or II, and the danger will disappear, after which the spring 24 will reseat the pressure valve.

The vacuum valve I8, like the pressure valve I4, is controlled by a spring, shown at 48, which, however, holds the vacuum-valve body 42 against its valve seat 44, in a direction opposite to that of the operation of the spring 24 of the pressure valve I4. Assuming, for example, that there is a failure of cold water in the supply pipe 4, a parg tial vacuum will become established in the boiler 2, and syphonage will take place. As a result of the suction thus` produced in the pipes, the atmospheric pressure in the chamber between the wall I2 and the cover member 3l will overpower the spring 48, permitting air from outside to be drawn into the relief or drain outlet pipe 84 and,

through the vacuum valve I8, and the casing 8, by way ofthe pipe I8 or II andthe pipe 1, into the boilerl2. Collapse of the boiler by atmospheric pressure, that might otherwise be caused by the partial vacuum in .the boiler 2, thus will be avoided. As soon as the danger from vacuum is over, the spring 48 will, of course, restore the valve I8 to its normal position, and when the water again flows from the mains into the coldwater pipe, it will expel the air thus introduced into the boiler. n

The temperature-controlled element I8 comprises a fusible plug 38` that normally closes a passage 38. In the event that the water in the boiler should approach the boiling point, the fusible plug 38 will become melted', whereupon the hot fluids in the boiler will likewise escape. At a later time, a new fusible plug 38 may be installed.

It will be noted that the short pipe I I, as shown in Figs. 'l and 10, leads directly up from the boiler 2, so as to be exposed directly to the conditions in the boiler. It will further be noted that the valves I4 and I8l and the temperature-controlled element I8 of the modifications shown in these Figs. 'l to 13 are all positioned on the said wall I2 of the casing 8, right in the passage between the cold-water supply and the boiler 2, just above the short pipe II that` leads up from the boiler, at a spot where the valves are readily and promptly responsive to the abnormal or critical boiler conditions before mentioned, and not at some more or less inaccessible point requiring a long time for the boiler conditions to cause a response in the said valves. The temperature-controlled element I8 of these modications will, therefore, respond in a manner similar to the valves I4 and I8. 'Ihe hot water in the boiler will rush into the chamber between the wall I2 and the cover member 38 through the passagev 38, and then will escape by way of the relief outlet or drain pipe 34, in the same manner as before described. ,The

pressure in the boiler becoming thus relieved, cold water will enter the boiler at the same time through the cold-water pipe 4.

This, however, is objectionable, because the path of the hot water from the boiler, by Way of the pipes 1 and I I, through the casing 8 to the temperature-controlled element I6, intersects the path of the cold water into the" boiler, by way of the pipes 4 and I I, through the casing 8. As soon asthe hot water in the casing 8 starts to flow through the passage 38, opened by the fusing of the fusible plug 36, therefore, the water in the wateresupply pipe 4 starts to flow into the boiler, by way of the casing 8, thereby tending to interfere with thefurther escape of the hot water from ,the boiler through the 'passage 38.

This diiliculty does not arise in connection with the operation of the pressure valve) I4, for the excess pressure in the boiler is greater than the pressure of the water in the water-supply 4; and it does not arise in connection with the operation of the vacuum valve I8, because the vacuum conditions in the boiler do not arise except when the water supply fails, and if the water supply were to be restored to the pipe 4, the water flowing therethrough into the boiler'would be a welcome substitution for the air that has entered the boiler through the vacuum valve I8. The vacuum valve I8 should preferably, indeed, be on the cold-Water side, so as to give immediate action upon the failure of -the water in the mains. The pressure valve I4, too, is preferably on the coldwater side. In the case of the temperature-controiled element I6, however, the water in the water-supply 4 is a detriment, and not a help, as it tends to interfere with the free flow ofy the hot water in the boiler through the vacuum valve il. The valves I4 and i6 and the temperature-controlled element I6 may be positioned similarly in the hot-water outlet pipe from` the boiler, instead of in the cold-water, inlet pipe, but this diillculty would still exist.

According to the preferred embodiment of the invention illustrated in Figs. 1 to 6, therefore, the escape oi the hot water from the boiler is by way of a path that is entirely separate and distinct from the path of flow of the cold water. As shown more particularly in Figs. 4, 5 and 6, a partition wall 50 separates the path of the coldwater flow in the casing 8 from the fusible plug I6, and the hot'water from the boiler is given access to the fusible plug by a separate pipe connection 6, as illustrated more particularly in Fig. 1. The inlet 6 to the temperature valve I6 is thus separate from the inlet 4 to the pressure valve I4 and the vacuum valve I8, though both valves i4 and I8 and the temperature-controlled element I6 have the same outlet or drain 34. The pressure valve I4 and the vacuum valve il are positioned in the path of ilow of the water from the water-supply pipe 4, directly in the path of the back-flow of the hot water from the boiler, between the water-supply pipe 4 and the boiler 2, but the temperature-controlled element 6 is positioned in the separate path 6 from the boiler 2. Upon the melting of the fusible plug 36, therefore, the hot water flows out through the passage 38 and the cold water simultaneously flows into the boiler through the pipe 1, each without interference by the other.

'I'he pipes 6 and 1 are both connected with the boiler. When the temperature of the boiler becomes excessive, therefore, hot water and steam have a tendency to back up in both the pipe 1 and the pipe 6. The excess temperature is usually, however, accompanied by excess pressure; and this excess pressure is usually suiliciently great to overcome the pressure of the cold water in the pipe 4, with the result that the hot water and steam travel upward, by way of the pipe 1, into the pipe i0 and against the side 52 of the partition wall 50. 'I'his side 52 of the partition wall has traveled to this fusible plug by conduction through the wall 50 and the water on the side 54 of the wall 50. As a result of this construction, therefore, the fusible plug 36 is caused to respond more quickly to temperature conditions in the boiler than would be the case if the wall 5I were absent. This wall 50, therefore, after the melting of the fusible plug 36, provides for a free flow of the hot water from the boiler through the passage 38, unhindered by the ilow of cold water into the boiler through the separate pipe 4, as before described; and it provides also that the fusible plug shall usually melt more promptly than would be .the case if one were to rely alone upon the excessheat from the boiler reaching the fusible plug 36 by conduction and connection of the hot water in the pipe 6.

'I'his construction, furthermore, provides an effective method oi circulating the hot water in contact with the fusible plug 36, ,to prevent stagnation. As the partition wall 56 is subjected to the cold water from the water-supply 4 on the said side 52, and to the hot water from the pipe 6 on the other side 54, the hot water on this side 64 is continually becoming cooled by conduction through the wall 56. As this water cools, it sinks. permitting other hot water in the pipe 6 to 'take its place. A continuous, circulating action thus takes place, which is aided by having the hot water from the pipe 6 reach the fusible plug 36 by two separate branches 56 and 56, as illustrated more particularly in Fig. 6.'

The casing I may, if desired, be provided with ya further, threaded outlet opening 46, which may be variously utilized. A stop valve 41, for example, may be threaded therein, to close the cold-water supply pipe 4, as illustrated in Fig. l2. 'I'his valveI 41 may be used in connection with any two, or all three, of the valve safety devices I4, i6 and il. The outlet opening 46 may further be utilized to provide for the insertion of a thermostat 43, as illustrated in Figs. 7 and 10. The thermostat may be connected by electric wires 50 to an electric-alarm system, such as a transformer 52, or the electric wiringy of the house, so as to give an alarm, as by means of `a bell 54, upon the occurrence of abnormal temperature conditions. Even if the temperature device should fail to operate, therefore, accidents may be manually avoided when the alarm has been given. Similar alarms may, of course, be provided for upon the occurrence of abnormal pressure and vacuum conditions.

The Wall I2 and the remaining parts of the casing l, and the inlet and the outlet openings 9 and 46 may be made in a single casting, as il lustrated.

Further modifications will occur to persons skilled in the art, and all such are considered to fall within the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

1. A relief device for a hot-water boiler comprising, in combination, a casing having separate hotand cold-water conduits therethrough, said conduits having a common thin wall section providing for rapid heat transfer therethrough, a portion of said hot-water conduit adjacent said common wall section providing for circulation of water within said portion, and a temperatureresponsive element `normally closing said hotwater conduit and located adjacent the said portion of the hot-water conduit for relieving excessive temperature conditions therein, 1 l f 2. A relief device for a hot-water boilercomprising, in combination, a casing having separate hot-water and cold-water conduits therethrough, said conduits being separated from each other, a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions therein, and means subjected to the cold water in the cold-water conduit for cooling the water in the neighborhood of the temperature-responsive element.

3. In combination, a hot-water boiler having a cold-water pipe for the admission of cold water to the boiler and a hot-water pipe for the travel of hot water from the boiler, and a relief device for the boiler comprising a casing having hotwater and cold-water conduits, the cold-water conduit connecting the cold-water pipe and kthe boiler, the hot-water conduit communicating with the hot-water pipe, the hot-water conduit being separated from the cold-water conduit and being disposed out of the path of travel of the hot water from the boiler through the hot-water pipe, a temperature-responsive element normally `closing said hot-water conduit for relieving excessive temperature conditions in the boiler, whereby, upon the occurrence of the said excessive temperature conditions, the hot water in the boiler will leave the boiler through the hot-water conduit and cold water will enter the boiler through the cold-waterpipe and the cold-water conduit, and means subjected to the cold water in the coldwater conduit for cooling the water in the neighborhood of the temperature-responsive element.

4. In combination, a hot-water boiler having a cold-water pipe for the admission of cold water to the boiler and a hot-water pipe for the travel of hot water from the boiler, and a relie! device for the boiler comprising acasing having hotwater and cold-water conduits, the cold-water conduit connecting the cold-water pipe and the boiler, the hot-water conduit communicating with the hot-water pipe, the hot-water conduit being separated from the cold-water conduit and being disposed out of the path of travel of the hot water from the boiler through the hot-water pipe, a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions inthe boiler, whereby, upon the occurrence of said excessive temperature conditions, the hot water in the boiler will leave the boiler through the hot-water conduit and cold water will enter the boiler through the cold-water pipe and the cold-water conduit, and means mounted in heat-transfer relation to said cold-water conduit for causing the hot water in the hot-water conduit to circulate.

5. A relief device for a hot-water boiler comprising, in combination, a casing having separate and non-communicating hot and cold-water conduits, and a temperature-responsive element no rmally closing said hot-water conduit for relieving 1 excessive temperature conditions therein and mounted in heat-transfer relation with said coldwater conduit.

6. In combination, a hot-water boiler, a casing having separate and non-communicating hot and cold-water conduits, said conduits communicating with the boiler at separate points, and a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions therein and mounted in heattransfer relation with said cold-water conduit.

'7. In combination, ra boiler, a hot-water pipe directly connected to the boiler for the travel of hot water directly from the boiler into and through the hot-water pipe, and a relief Ldevice for the boiler comprising a casing having separate hot-water and cold-water conduits provided with a common metal-wall section, the hot-water conduit being disposed out of the path of direct travel of the hot water from the boiler through the hotwater pipe, a branch pipe connecting the hotwater conduit with the hot-water pipe, whereby the hot water normally travels directly out of the boiler into and through the hot-water pipe but without traveling through the hot-water conduit, a temperature-responsive element for relieving excess temperature conditions in the boiler normally closing the hot-water conduit, and means providing two passages to the hot-water conduit for the hot water from the boiler.

yil. In combination, a hot-water boiler having a cold-water pipe for the admission of cold water to the boiler and a hot-water pipe for, the travel amants of hot water i'rom the boiler, and a relie! device for the boiler comprising a casing having separate hot-water and cold-water conduits provided with a common thin metal-wall sectiomthe cold-water conduit connecting the cold-water'pipe and the boiler, the hot-water conduit communicating with the hot-water pipe, the hot-water conduit being disposed out of the path of travel oi.' the hot water from the boiler through the hot-water pipe, and a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions in the boiler, whereby, upon the occurrence'of said excessive temperature conditions, the hot water in the boiler will leave.

the boiler through the hot-water conduit and cold water will enter the boiler through the cold-water pipe and the cold-water conduit.

9. In combination, a hot-water boiler having a cold-water pipe tor the admission of cold water to the boiler and a hot-water pipe for the travel of hot water from the boiler, and a relief device for the boiler comprising a casing having separate hot-water and cold-waterl conduits provided with a common thin metal-wall section, the cold-water conduit connecting the cold-water pipe and the boiler, the hot-water conduit communicating with the hot-water pipe, the hot-water conduit being disposed out of the path of the travel ot the hot water from the boiler through the hot-water pipe, a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions in the boiler, whereby, upon the occurrence of the said excessive temperature conditions, the hot water in the boiler will leave the boiler through the hot-water conduit and cold water will enter the boiler through the cold-Water pipe and the cold-water conduit, and a pressure valve communicating with the cold-water conduit for relieving excessive pressure conditions in the boiler. whereby, upon the occurrence of the said excessive pressure conditions, the hot water in the boiler will leave the boiler through the pressure valve and the cold-water conduit.

10. In combination, a hot-water boiler having a cold-water pipe for the admission of cold water to the boiler and a hot-water pipe for the travel of hot water from the boiler, and a relief device for the boiler comprising a casing having separate hot-water and cold-water conduits provided with a common thin metal-wall section, the coldwater conduit connecting the cold-water pipe and the boiler, the hot-water conduit communicating with the hot-water pipe, the hot-water lconduit being disposed out of the path of the travel of the hot water from the boiler through the hot-water pipe, a temperature-responsive element normally closing said hot-water conduit for relieving excessive temperature conditions in the boiler, whereby, upon the occurrence oi the said excessive temperature conditions, the hot water in'the boiler will leave the boiler through the hot-water conduit and cold swater will enter vthe biler throughv the colda cold-water pipe for the admission of cold water to the boiler and a hot-water pipe for the travel of hot water from the boiler, and a relief device i'or the boiler comprising a casing having separate hot-water and cold-water conduits provided with a common thin metal-wall section, the cold-water conduit connecting the cold-water pipe and the boiler, the hot-water conduit communicating with the hot-water pipe, the hotwater conduit being disposed out of the path of thetravel ofthe hot water from the boiler through the hot-water pipe, a temperature-responsive element normally closing said hotwater conduit for relieving excessive temperature conditions in the boiler, whereby, upon the occurrence of the said excessive temperature conditions, the hot water in the boiler will leave the boiler through the hot-water conduit and cold water will enter the boiler through the cold-water pipe and the cold-water conduit, and a pressure valve and a vacuum valve communicating with the cold-Water conduit for respectively relieving excessive pressure and vacuum conditions in the boiler, whereby, upon the occurrence of the said excessive pressure conditions, the hot water in the boiler will leave the boiler through the pressure valve and the coldwater conduit, and whereby, upon the occurrence of the said excessive vacuum conditions, air will enter the boiler through the cold-water conduit and the vacuum valve.

12. In combination, a hot-water boiler having a cold-water pipe for the admission of cold water to the boiler and a hot-water pipe directly connected to the boiler for the travel of hot water directly from the boiler into and through the hot-water pipe, and a relief device for the boiler comprising a casing having hot-water and coldwater conduits provided with a common thin metal-wall section separating the hot-water conduit from the cold-water conduit, the coldwater conduit connecting the cold-water pipe and the boiler, whereby the cold water travels from the cold-water pipe into the boiler by way oi' the cold-water conduit, the hot-water conduit being disposed out of the path of direct travel of the hot water from the boiler through the hot-water pipe, a branch pipe connecting the hot-water conduit with the hot-water pipe, whereby the hot water normally travels directly out of the boiler into and through the hot-water pipe but without traveling through the hotwater conduit, and a temperature-responsive element for relieving excessive temperature conditions in the boiler normally closing the hotwater conduit, whereby, upon the occurrence of said excessive temperature conditions, the hot water in the boiler will leave the boiler through the hot-water conduit and cold water will enter the boiler through the cold-water pipe and the cold-water conduit.

13. A relief device for a boiler comprising a casing having a wall provided with three passages therethrough, namely, a pressure-valve passage, a vacuum-valve passage and a temperature-device passage, three relief elements, namely, a pressure valve, a temperature device and a vacuum valve respectively associated with thepassages, the temperature device comprising a temperature-controlled element normally closing the temperature-device passage, the pressure valve normally closing the pressure-valve passage, and the vacuum valve normally closing the vacuum-valve passage, a cover member connected to the wall on one side of the wall so as to enclose the relief elements, the cover member being detachable to permit access to all the relief elements, and an outlet connecting the cover member with the atmosphere to cause the relief elements to be subjected to the pressure of the atmosphere at the said one side of the wall, the relief elements being adapted to be connected to the boiler on the other side of the wall, the temperature-controlled element being responsive to temperature conditions in the boiler to permit the now of water from the boiler through the temperature-device passage, the cover member and the outlet to the atmosphere when the temperature in the boiler exceeds a predetermined value, the pressure valve being responsive to pressure conditions in the boiler to permit the flow of water from the boiler through the pressure-valve passage, the cover member and the outlet to the atmosphere when the pressure in the boiler exceeds a predetermined value, and the vacuum valve being responsive to vacuum conditions in the boiler to permit the flow of air from the atmosphere by way of the outlet and through the cover member and the vacuum-valve passage to the boiler when the vacuum in the boiler exceeds a predetermined value.

14. Apparatus of the character described for use with a boiler having, in combination, a relief device external to the boiler, the reliefvdevice having a wall provided with two passages therethrough, a temperature-controlled element normally closing one of the passages, a pressure valve normally closing the other passage, means on one side of the wall connecting the boiler with the temperature-controlled element and the pressure valve at one side of the passages, an outlet communicating with the atmosphere at the other side of the wall, and a cover member mounted on the said other side of the wall connecting the outlet with the temperature-controlled element and the pressure valve at the other side of the passages to cause the temperature-controlled element and the pressure valve to be subjected to the pressure of the atmosphere at the said other side of the wall, the temperature-controlled element being responsive to temperature conditions in the boiler to permit the ilow of water from the boiler through the said one passage, the cover member and the outlet to the atmosphere when the temperature in the boiler exceeds a predetermined value, and the pressure valve being responsive to pressure conditions in the boiler to vpermit the ilow of water from the boiler through the pressurevalve passage, the cover member and the outlet to the atmosphere when the pressure in the boiler exceeds `a predetermined value, the cover member being detachable from its mounting on the said other side of the wall to permit access to the temperature-controlled element'and the pressure valve.

l5.' Apparatus of the character described for use with a boiler having, in combination, a relief device external to the boiler, the relief device having a wall provided with two passages therethrough, a temperature-controlled element normalfy closing one of the passages, a vacuum valve normally closing the other passage, means on one side of the wall connecting the boiler with the temperature-controlled element and the vacuum valve at one side of the passages, an outlet communicating with the atmosphere at the other side of the wall, and a cover member mounted on the said other side of the wall connecting the outlet with the temperature-controlled element and the vacuum valve at the other side of the passages to cause the temperaturecontrolled element and the vacuum valve to be subjected to the pressure 'of the atmosphere at the said other side of the wall, the temperaturecontrolled element being responsive to temperature conditions in the boiler to permit the ilow of water from the boiler through the said one passage, the cover member and lthe outlet to the atmosphere when the temperature in the boiler exceeds a predetermined value, and the vacuum valve being responsive to vacuum conditions in the boiler to permit the ilow of air from the atmosphere by way of the outlet and through the cover member and the vacuum-valve passage to the boiler when the vacuum in the boiler exceeds a predetermined value, the cover member being detachable to permit access to the temperature-controlled element and the vacuum valve.

r16. Apparatus of the-character described for use with a boiler having, in combination, a relief device external to the boiler, the relief device having a wall provided with three passages therethrough, namely, a pressure-valve passage, a vacuum-valve passage and a temperature-controlled-element passage, three relief elements, namely, a pressure valve, a temperature-controlled element and a vacuum valve respectively associated with the passages, the temperaturecontrolled element normally closing the temperature-controlled-element passage, the pressure valve normally closing the pressure-valve Vpassage, the vacuum valve normally closing the vacuum-valve passage, means on one side of the wall connecting the boiler with the temperaturecontrolled element, the pressure valve and the vacuum valve, at one side o! the passages, an outlet communicating with the atmosphere at the other side of the wall, and a cover member mounted on the said other side of the wall con'- necting the outlet with the temperature-co trolled element, the pressure valve and the vacuum valve at the other side of the passages to cause the temperature-controlled element, the pressure valve and the vacuum valve to be subjected to the pressure of the atmosphere at the said other side of the wall, the temperaturecontrolled element being responsive to temperature conditions in the boiler to permit the now of watcrvi'rom the boiler through the said one passage,vthe cover member and the outlet to the atmosphere when the temperature in the boiler exceeds a predetermined value, the pressure valve being responsive to pressure 'conditions in the boiler to permit the now of water from the boiler through the pressure-valvev passage, the cover member and the outlet to the atmosphere when the pressure in the boiler exceeds'a predetermined value, and the vacuum valve being responsve to vacuum conditions in the boiler to permit the ilow of air from the atmosphere by way of the outlet and through the cover member and the vacuum-valve passage to the boiler when the vacuum in the boiler exceeds a predetermined value, the cover member being detachable to permit access to the temperature-controlled element and the pressure and vacuum valves.

JACOB PODOLSKY. 

